Actually i started preparing for the beta exam in december with the Mastering EJB3.0 book and Specs which i read quite well but i wasn't convinced i was ready for the beta exam.

When i finally decided to write i read mostly Java persistence,Persistence Units and Persistence Contexts, Entity Operations and Contract & Lifecycle (Session Beans) for the EJB Specs because all the author made reference to them one way or the other.

And then Transactions,Exceptions and Security Management from Mastering EJB3.0.

And for O'rielly Enterprise Java Beans 3.0 and SCBCD 5.0 Study Guide by Mikalai Zaikin were straight to the point and very very helpful all the way....